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jarptica [38.1K]
3 years ago
14

How many elements are there

Chemistry
1 answer:
yawa3891 [41]3 years ago
4 0
There are 118 known elements
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You are working in the lab, how many grams of solute you need to make 200.0 g of 3.4% of solution?
Goryan [66]

Answer:

6.8g of solute are needed

Explanation:

Percent by mass, (w/w%) is defined as the mass of solute in 100g of solution. A solution that is 3.4% contains 3.4g of solute in 100g of solution. That means to make 200g of solution are required:

200g solution * (3.4g solute / 100g solution) = 6.8g of solute are needed

6 0
3 years ago
g Calculate the [OH-] from the results of your titrations. Explain your calculations2. Calculate the [Ca2+]. Explain your calcul
RideAnS [48]

Answer:

Explanation:

*Since the titration is between the strong acid HCl and the strong base Ca(OH)2, the pH at the equivalent point should be 7. On interpolation, we will obtain that 9.50mL and 9.82 mL of HCl is required to completely neutralized the given Ca(OH)2 solution.

*pH at the equivalence point =7

we know that pH + pOH = 14

Hence pOH= 14-7=7

pOH= -log(OH-)

The concentration of OH-= 10-pH= 1X10-7 M

One reason for the low solubility may be the higher reaction temperature, Another reason is the common ion effect.

3 0
3 years ago
Help with number 3 plz help due tomorrow!!!!!!!!!!
IceJOKER [234]

Answer:

which one?

Explanation:

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4 0
3 years ago
Read 2 more answers
How many cu atoms are present in a piece of sterlingsilver jewelry weighing 33.24 g ? (sterling silver is a silver–copper alloy
emmasim [6.3K]

The mass of piece of sterling silver jewelry is 33.24 g. It contains 92.5% silver Ag by mass. Since, sterling silver is an alloy of Ag-Cu thus, percentage of Cu will be:

% Cu=100-92.5=7.5%

Thus, mass of copper will be:

m_{Cu}=\frac{7.5}{100}\times 33.24 g=2.493 g

Molar mass of Cu is 63.546 g/mol, thus, number of moles of Cu can be calculated as follows:

n=\frac{m}{M}

Here, m is mass and M is molar mass.

Putting the values,

n=\frac{2.493 g}{63.546 g/mol}=0.03923 mol

Now, in 1 mole of Cu there are 6.303\times 10^{23}atoms thus, in 0.03923 mol, number of Cu atoms will be:

0.03923 mol\times 6.303\times 10^{23}atoms=2.363\times 10^{22} atoms

Thus, number of atoms of Cu will be2.363\times 10^{22} atoms.


8 0
3 years ago
A Question 2 (2 points) Retake question
Ksivusya [100]

Answer:

3.3765 Mol O2

Explanation:

There is no work for this problem

3 0
3 years ago
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